During the construction of the first of two parallel pipelines constituting the San Diego Aqueduct, it was found that the compacted soil bedding specified did not always provide the uniform dense mass desired for bearing. Studies were undertaken at that time to develop an economical method for improving the bedding. It was found that pervious sandy and gravelly soils could be consolidated uniformly to high density by saturating and vibrating methods. It was also found that this type of bedding was more economical than the inferior compacted bedding. Savings resulted from the use of narrower trenches, as less working space was required, and from ease of placement. This paper presents information on the laboratory studies that were performed for the development of procedures and materials criteria in connection with the work. The bedding requirements and construction procedures used in the construction of the second pipeline of the aqueduct are also described.